ADual-rotor permanent magnet induction motor (DRPMIM) is an induction motor having a rotor inside the stator with a second rotor on the outside of the stator. This rotor arrangement can increase power density and efficiency and reduce cogging torque.[1][2]
In one layout, the motor has an ordinary induction motor stator. A squirrel-cage rotor connected to the output shaft rotates within the stator at slightly less than the rotating field from the stator. Within the squirrel-cage rotor is a freely rotating permanent magnet rotor, which is locked in with rotating field from the stator. The effect of the inner rotor is to reenforce the field from the stator.
In another layout, one rotor is inside the stator with a second rotor on the outside of the stator. This rotor arrangement can increase power density and efficiency and reduce cogging torque.
Because of their greater power density dual-rotor permanent magnet induction motors are being considered for use in electric vehicles.
References
^Diao, Tongshan (2015). "Study on Dual-Rotor Permanent Magnet Induction Motor and Performance". The Open Electrical & Electronic Engineering Journal. 9 (1): 584–590. doi:10.2174/1874129001509010584. ISSN1874-1290.
^Hwang, Myeong-Hwan; Lee, Hae-Sol; Yang, Se-Hyeon; Lee, Gye-Seong; Han, Jong-Ho; Kim, Dong-Hyun; Kim, Hyeon-Woo; Cha, Hyun-Rok (2019). "Cogging Torque Reduction and Offset of Dual-Rotor Interior Permanent Magnet Motor in Electric Vehicle Traction Platforms". Energies. 12 (9): 1761. doi:10.3390/en12091761. ISSN1996-1073.{{cite journal}}: CS1 maint: unflagged free DOI (link)